Method of and furnace for uniting metal parts by fusion



Feb. 14, 1928. 1,659,559

c. STEENSTRUP METHOD OF AND FURNACE FOR UNITING METAL PARTS BY FUSION Filed 29. 1926 Inveni'or Chrislian STeensTr-up 5 'His ATTorne Patented Feb. 14, 1928.

UNITED STATES PATENT OFFICE.

CHRISTIAN STEENSTRUP, OF SCHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

METHOD OF AND FURNACE FOR UNITING- METAL PARTS BY FUSION.

Application filed May 29,

The present invention relates to the method of uniting metal parts by fusion, us ng for the purpose a metal of lower melting point such as copper for example, and also to a furnace for carrying out said method and in which a non-oxidizing atmosphere is maintained.

In uniting metal parts made of steel for' example, in this manner they are commonly tightly or closely fitted to each other so as to render the spaces or joints between. them of a capillary nature. After this is done, it 1s the custom to temporarily clamp the parts in their proper positions one with respect to the other. It is also the practice to place a heavy Weight on the parts to be united in such manner as to prevent the parts from warping and to force them into intimate contact when softened by heat. This weight which is made of metal is necessarily heavy and being within the furnace a great deal of heat is absorbed thereby, heat which is expensive, being obtained from electricity through suitable means such as resistors. Further, the weight is inconvenient to handle and the handling is, of course, additional to the necessary work, and requiring as it does an extra operation both in loading and unloading the furnace.

I have invented or discovered a way whereby for certain classes of work these independent weights may be dispensed with and the articles themselves utilized to furnish the necessary force or pressure to ensure proper contact pressure between the parts which are to be united.

Viewed from another and somewhat broader aspect, my invention comprises a continuous fusing process in which the arti cles to be treated are fed into an elongated furnace chamber at one end and are removed as finished articles at the other, said articles in their passage through the cham her being maintained in firm contact with each other so that distortion of the parts undergoing treatment is prevented and so that complete union of the parts which are to be united is effected.

My invention is particularly applicable to flat plates having internal chambers and which are used for heating and cooling purposes. Such plates have wide application in the mechanical arts and one particular application is in electric household refrigerators. My invention is primarily useful 1926'. Serial No. 112,716.

Where each element is a duplicate or substantial duplicate of the others and for protduct'lon of these elements in large quanti- In carrying out my invention the elements to be fused are prepared in any suitable manner withthe necessar amount of copper and in this respect may follow the present practice. Considering the case of heating and cooling plates which are made of steel, have fiat top and bottom plates, rather thin and of considerable surface area between which are located suitable spacers to form internal chambers. These are piled one on top of the other in a tower-like furnace, the interior of which is suitably fitted with electric resistors. The top and bottom of the tower are closed and a controlled supply of hydrogen admitted thereto and a pressure maintained therein which is slightly above atmosphere to prevent entrance of air. Assuming the furnace to be properly charged, the fused or finished plates are removed one by one from the bottom of the stack and the unfinished, cold plates which are to be fused are fed one by one into the tower at'the top. For both these purposes suitable means are provided which in addition to their function as loading and unloading devices, may also serve to prevent the escape of the non-oxidizing gas and the entrance of air to the heating chamber.

The heating resistors surround the articles or elements to be treated and by preference do not extend quite to the top or to the bottom of the furnace. This means that the lowest plates will pass through a cooler region before being removed, and the articles at the top will have a chance to gradually increase in temperature before entering the hot zone where the resistors are located. The weight of the articles above those which are at fusion temperature is sufiicient to firmly press the parts of the latter into firm contact and because they pass from the hot zone into one below which is enough cooler to permit the fusing metal to harden, the bottom plate of the stack can be readily removed. To prevent the plates from being accidentally fused together suitable, nonfusing spacers are provided between each pair of plates wherever necessary.

In the accompanying drawing I have illustrated a type of furnace designed to operate in accordance with my invention. For

, grannnatic manner, Fig. 1 showing the fur-' simplicity it is shown in a somewhat dianace in vertical section and Fig.2 a crosssection on llne 22, of Fig. 1.

1 indicates a metallic shell or casing of cylindrical or other form depending upon the shape of the plates and standing on one end. It is heavily lined with heatinsulating material 2. About'the middle portion thereof is located the electric resistors 3 which are supplied with current from a suitable source. It will be noted that they do not extend to the top or to the bottom of the furnace chamber so that the unfinished articles to be fused are gradually heated as they descend into the hot zone and are gradually cooled as they leave it so as to permit the fusing metal to harden. The resistors may. be connected in any suitable manner to a source of current supply and the amount of current admitted is subject to ordinary control devices. The zones above and below the. res'stors may be made longer or shorter depending upon the character of the articles to be treated.

At the bottom of the furnace is a 1'ectan-' gular reciprocating slide 4 of about the width of the articles 5 which in this case are chambered plates. At the rear of the slide is a shoulder 6 adapted to engage one plate at a t me. As the slide is moved to the right the article at the bottom of the stack is moved with it to one side of the furnace where it can be removed. The slide is also provided with a flat portion 7 which sustains the stack during the withdrawing or unloading operation. Upon pushing the slide back to its normal position the stack drops to the lower part of the slide and occupies the position shown. The slide may be actuated by hand or power depending upon the we ght of the articles in the stack. As shown, it is actuated by a double rack and pinions. To preserve the alignment of the articles in thc'stack suitable guides 8 are or may be employed. These may be made of chromium steel which does not fuse with copper.

In order to load the furnace a work table 9 is situated at one side of the furnace. On the top of the furnace is a second rectangular slide 19 and which is provided with an electro-magnet 11 by means of which the articles 5 can be picked up from the table when the slide is moved to the right to such position that the magnet registers with the article. The magnet on being energized picks up the article after which the slide is pushed back and the circuit of the magnet opened by a switch which permits the article to drop on the stack. This slide may be operated by hand or by .power as desired. When operated by power the arrangement used for the lower slide may be employed. By making reasonably good fits both of the slides will and unloading operations.

Hydrogen or other gas is admitted to the furnace by the conduit 12 subject to the control of a valve 13. The pressure of the gas wfthin the furnace should be slightly above that of the atmosphere to prevent the entrance ofair.

In order to prevent the articles from being fused to each other should there be an excess of copper, spacers 14 are placed between'them. For this purpose asheet of non-fusing metal, asbestos or equivalent material may be used and placed on top of each article when in the work or loading table, 9.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The method of uniting articles by fu-,

to the other end thereof, n'iaintaining endwise pressure on the stack to cause firm seating of the parts of the articles to be fused, and maintaining a non-oxidizing atmosphere within the furnace.

The method of uniting articles by fusion of metal wh'ch comprises arranging the articles and the necessary fusion metal in a stack within a furnace whereby the weight of the upper portion of the stack exerts pressure on the articles below, heating articles in the stack to fusing temperature, and removing the fused articles from the lower end of the stack.

3. The method of uniting articles by fusion of metal which comprises arranging the articles and the necessary fusion metal in a vertical stack within a furnace whereby the we ght of-the upper portion of the stack exerts pressure on the articles below, heating a portion of the stack to fusing temperature, maintaining an atmosphere of non-oxidizing gas around the stack, and removing the fused articles from the lower end of the stack.

4. The method of unitin; articles by fusion of metal which comprises arranging the articles and the necessary fusion metal in a vertical stack within a furnace whereby the weight of the upper portion of the stack exerts pressure on the articles below, heating the articles in the stack to fusing temperature as they descend, maintaining an atmosphere of non-oxidizing gas around the stack, removing fused articles from the bottom and of the stack, and adding articles to be fused at the top.

5. The method of fusing metal articles, each comprisin two or more pieces, which comprises assem ling the partially completed articles and fusion metal in a vertical stack within a closed furnace, with non-fusing spacers between the articles, whereby the weight of the articles on the upper portion of the stack exert pressure on those in the lower portion, heating the intermediate portion of the stack to fusing temperature, maintaining a supply of selected gas within the furnace to facilitate fusion and prevent oxidization, ren'ioving the finished articles from the bottom of the stack after the fusing metal has hardened, and adding articles to the top of the stack as the finished articles are removed.

6. The method of fusing metal articles, each comprising two or more pieces which comprises assembling the articles and the fusing metal in a stack, whereby the weight of the articles in the upper part of the stack exert. pressure on the heated articles in the lower part of the stack, slowly moving the articles into and out of a hot zone in the furnace. maintaining a non-oxidizing gaseous atmosphere within the furnace, removing finished articles from the bottom of the stack, and supplying unfinished articles to the top of the stack.

7. In an electric furnace, the combination ol a member which has an elongated chamher to receive a stack of articles to be treated, electric heating elements located within the chamber and which surround a portion of the stack, means for removing articles from one end of the stack, other means for adding articles to the other end of the stack, and means for maintaining a non-oxidizing atmosphere around the articles and the heating elements.

8. In an electric furnace, the combination of a vertical member which has a central opening to receive a stack of articles to be treated. heating elements located in the member and about the articles to be treated, a means for removing the finished articles from the bottom of the stack, and means for adding articles to the top of the stack as the finished articles are removed.

9. In an electric furnace, the combination of a Vertical member which has acentral opening to receive a stack of articles to be treated, electric resistors which surround the middle portion of the stack for heating it and so arranged that as the articles descend their temperature will be gradually increased to the maximum required and later decreased, a means for sliding the finished articles from the bottom of the stack, and means for loweringmnfinished articles on top of the stack.

10. In an electric furnace, the combination of a vertical member which has a central opening to receive a stack of articles to be treated, electric resistors which surround the middle portion of the stack for heating it and so arranged that as the articles dcscend their temperature will be gradually increased to the maximum required and later decreased, aslide for pulling the finished articles from the bottom of the stack, and a means for picking up the articles. moving them into register with the top of the stack,

and then lowering them.

11. In an electric furnace, the combination of a member which has an elongated chamber to receive a stack of articles to be treated, electric heating elements located within the chamber and which surround a portion of the stack, means for renioving articles from one end of the stack, other means for adding articles to the other end of the stack, guiding means for directing the added articles to their proper positions in the stack and to preserve their respective positions. and a controllable means for maintaining a non-oxidizing atmosphere Within said chamber.

12. The method of uniting the parts of composite metal articles by fusion of metal, which comprises arranging the articles in stacked formation and with the parts assembled, together with suitable fusing metal, in a furnace chamber which directs movement. of the stack in a vertical direction, causing the stack to move by removing articles from one end of the stack and adding articles to the other end of the same, maintaining a non-oxidizing atmosphere in the furnace chamber, and heating the articles in the stack progressively as they move through the chamber.

In Witness whereof, I have hereunto set my hand this 28th day of May, 1926.

CHRISTIAN b'TEEN S'lR-Ul. 

